The death toll from a massive explosion that shook the northern Chinese port city of Qingdao has risen to 35, reported state-owned China Central Television (CCTV) on Friday afternoon, making it one of the most deadly industrial accidents this year.

CCTV online updates reported that as of 5.40pm on Friday, at least 166 people were injured and in hospital. The powerful explosion occurred near the southern gate of the Lidong Chemical Plant in the city's Huangdao district in the morning. Xinhua said it was still verifying other casualty counts.

An underground oil pipeline ruptured at around 3am, causing an oil spill, the Qingdao municipal government said. The emergency repair work that followed led to a fire and caused the explosion, it said. Two separate fires were extinguished by 1pm.

Qingdao pipeline leak explosion

The ruptured pipeline was part of a 176-km underground pipeline project that pumps crude oil from Qingdao to Weifang, also in Shandong Province. Xinhua says the pipeline was operated by oil giant Sinopec.

Crude oil leaked by the pipeline spilled into the harbour basin near Jiaozhou Bay at 3am in the night to Friday, according to a preliminary report by the Qingdao Municipal Environmental Protection Bureau. The operating company stopped the oil flow in the broken pipeline around 3.15am and attempted to contain the contamination of several hundred square meters large area of polluted water. Contamination at sea extended over three square kilometres, the report said.

Oil that entered local rain drainage pipes exploded at 10.30am, the report said.

Pictures published by local media and witnesses on the social media platform Weibo show corpses, damaged streets and overturned vehicles. One picture, purportedly published by an passenger on board an airplane which was flying over Qingdao after the explosion showed black smoke rising through the sky